Zhang Zhe, Zhang Yue, Yang Dong C, Zhang Jin L
a College of Plant Protection , Agricultural University of Hebei , Baoding , Hebei , China.
b College of Plant Protection , Nanjing Agricultural University , Nanjing , Jiangsu , China.
J Environ Sci Health B. 2018;53(7):476-485. doi: 10.1080/03601234.2018.1455344. Epub 2018 Mar 29.
To investigate the degradation activity of the manganese ABC transporter, vegetative catalase 1 and acetoin dehydrogenase E1 from Bacillus subtilis YB1, the proteins were prokaryotically expressed and purified. Assay results showed that the three enzymes were able to degrade nicosulfuron (2- (4,6-dimethoxypyrimidine-2-pyrimidinylcarbamoylaminosulfonyl) -N,N-dimethylnicotinamide), with vegetative catalase 1 exhibiting the highest activity. To further examine the degradation pathway, the degradation products of the three enzymes and the YB1 strain were detected by liquid chromatography-mass spectrometry(LC-MS). The nicosulfuron degradation products of the three enzymes were consistent with those of the YB1 strain, indicating the presence of two pathways: one due to cleavage of sulfonylurea bridges and ring-opening of 1-(4,6-dimethoxy-pyrimidin-2-yl)-3-(2-methyliminomethanesulfonyl-acetyl)-ureaas the pyrimidine ring, yielding the product; and the another due to cleavage of a sulfonylurea bridge, yielding 4,6-dihydroxy pyrimidine (111 m/z), 2-ylamine -4,6-dimethoxy pyrimidine and ((4-(dimethycarbamoyl)pyridine-2-yl)sulfonyl)carbamic acid as products, which were further degraded to 4,6-dihydroxy pyrimidine and N,N-dimethyl-2-sulfamoyl-isonicotinamide. The above results reveal a major contribution of extracellular enzymes to the degradation of nicosulfuron by the YB1 strain. Our data help in elucidation of the mechanism of nicosulfuron bio-degradation and may facilitate the construction of engineered strains.
为了研究枯草芽孢杆菌YB1中锰ABC转运蛋白、营养型过氧化氢酶1和乙偶姻脱氢酶E1的降解活性，对这些蛋白质进行了原核表达和纯化。测定结果表明，这三种酶都能够降解烟嘧磺隆（2-(4,6-二甲氧基嘧啶-2-嘧啶基氨基甲酰基磺酰基)-N,N-二甲基烟酰胺），其中营养型过氧化氢酶1的活性最高。为了进一步研究降解途径，通过液相色谱-质谱联用仪（LC-MS）检测了这三种酶和YB1菌株的降解产物。这三种酶的烟嘧磺隆降解产物与YB1菌株的降解产物一致，表明存在两条途径：一条是由于磺酰脲桥的断裂和1-(4,6-二甲氧基嘧啶-2-基)-3-(2-甲基亚氨基甲磺酰基乙酰基)-脲嘧啶环的开环，产生产物；另一条是由于磺酰脲桥的断裂，产生4,6-二羟基嘧啶（111 m/z）、2-氨基-4,6-二甲氧基嘧啶和((4-(二甲基氨基甲酰基)吡啶-2-基)磺酰基)氨基甲酸作为产物，这些产物进一步降解为4,6-二羟基嘧啶和N,N-二甲基-2-磺酰基异烟酰胺。上述结果揭示了细胞外酶对YB1菌株降解烟嘧磺隆的主要贡献。我们的数据有助于阐明烟嘧磺隆生物降解的机制，并可能促进工程菌株的构建。
